Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor. The rotor typically includes a rotatable hub having one or more rotor blades attached thereto. A pitch bearing is typically configured operably between the hub and a blade root of the rotor blade to allow for rotation about a pitch axis. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Large commercial wind turbines are prone to lightning strikes that can damage the rotor blades, particularly at the blade root. In this regard, it is a common practice to provide the turbine blades with lightning receptors spaced along the longitudinal length of the blade so as to capture and conduct the lightning strikes to ground. The conventional configuration of these receptors, however, results in difficult, expensive, and time-consuming maintenance and diagnostic procedures that typically requires a crane to externally access each receptor. The conventional configuration does not offer a means to verify the continuity of the receptors within a blade without accessing and testing each receptor individually. In addition, the effectiveness of the receptors depends on the integrity and reliability of a single conductive path along the blade. Failure (i.e., a break) of this path renders any upstream receptors essentially useless.
Efforts have been made to devise alternative lightning protection systems for wind turbine blades. For example, U.S. Patent Publication No. 2009/0129927 describes a system that avoids blade mounted receptors altogether by mounting radially extending lightning receptors to the rotor hub, with the receptors extending between the blades. This configuration, however, may result in increased weight, drag, and noise, and an overall decrease in the capability of the turbine.
Accordingly, the industry would benefit from an improved lightning protection system that addresses the aforementioned issues. Particularly, a lightning protection system for a wind turbine that prevents damage to the blade root would be advantageous.